This invention concerns multi-speed drives and more particularly a two-speed clutch drive in which the rotary drive from the input shaft is transmitted to a rotary output member in either a high speed direct drive mode or in a reduced speed mode in which the output member is driven at a slower speed than the input shaft.
Such multi-speed drives are utilized in a variety of applications such as in clothes washing machines where an electric drive motor is employed to cause rotation of the washing machine agitator and basket in order to suit the washing action and spin extraction cycles to differing wash cycles in which the washing and drying action are adapted to different fabric types, i.e., slow speeds for delicate fabrics and normal or high speed for regular fabric.
One approach for producing such multi-speed drive is the use of a two-speed clutch in which the output shaft of a drive motor is transmitted via a clutch having a first mode in which the rotation of the input motor shaft is transmitted to an output member at the same rotative speed. In a second mode, a controlled slip of the clutch produces a reduced speed of the output member relative to the rate of rotation of the drive motor.
This arrangement is described in U.S. Pat. No. 2,869,699. The two-speed drive depicted in this patent includes an inner drum constituting a rotary input member surrounding the motor shaft and a concentric outer drum constituting the rotary output member which is adapted to drive the washing machine transmission input. In these applications, the motor is also adapted to directly drive the washing machine drain pump by means of a motor shaft extension extending from the two-speed drive clutch and fitted with a coupling connected to the input shaft of the pump or pumps.
The clutch includes centrifugally actuated clutch shoes carried on a carrier plate which is fixed to the motor shaft and are adapted to engage the inside of the inner drum upon rotation of the motor shaft to establish drive from the motor shaft to the clutch inner drum. The centrifugal action limits the torque loading of the motor for heavy laods, such as initial spin down of a full basket.
The outer drum and inner drum are adapted to be drivingly connected by two separate clutching interconnections which when operated respectively establish either low speed or high speed drive between the inner drum and the outer drum.
The low speed clutch arrangement includes clutch shoes which are drivingly connected to the output drum and which are frictionally engaged with the inner drum exterior by spring applying pressure, which pressure is reduced with increasing rotative speed of the outer drum due to a centrifugal disengagement force which is generated acting to disengage the so-called slip shoes. The result of this action is to establish a reduced constant output speed drive from the inner drum to the outer drum.
Direct drive is established by means of a carrier plate upon which is mounted two sets of pivotally mounted clutch shoes. Upon rotation of the carrier plate, one set moves into engagement with the exterior outside diameter of the inner drum and the other set moves into engagement with the outer drum to establish drive between the outer drum and inner drum at a direct drive ratio.
The design relies on control over the drive to the carrier plate to establish the direct drive condition. The carrier plate is rotatably mounted on the motor shaft by means of a friction bearing and tends to be accelerated by rotation of the motor shaft which will in turn establish a driving connection of the inner drum and increase the speed of rotation of the carrier plate until direct drive between the inner and outer drums is achieved.
The low speed drive is created by a solenoid actuated braking shoe moved into engagement with the carrier plate, preventing rotation of the carrier plate and thus avoiding the direct drive condition, until the actuator releases the locking brake to enable the friction bearing to rotate the carrier plate as described.
The presence of this second carrier plate requires the assembly of the clutch to the motor shaft and of the various separate components in the assembly of the extension shaft to the motor shaft at the assembly of the unit. This in turn necessitates a clamping connection between the motor shaft and the shaft extension occupying a portion of the axial depth of the unit. This appreciably increases the expense of the unit since motor shafts must be machined to enable the clamping connection to be made. Separate clamping components and fasteners are also of necessity employed. The alignment of the motor shaft and shaft extension is difficult to maintain, whicy may cause noise and unbalance of the shaft extension.
In addition, the presence of the clamp limits the bearing support available for the inner drum since the clamp connection preemps the axial space available for such bearing. The carriage plate and clutch shoes represent a significant cost item, as well as does the related components, such as the ball bearing required to support the same on the motor shaft.
The presence of the clamp also increases the depth of the clutch unit and the attendant long motor extension shafts required.
This arrangement also requires a resilient support of the centrifugally actuated shoes to limit the noise due to vibrations being transmitted between the inner and outer drums.
It is therefore an object of the presen invention to provide such a two-speed clutch of this general type in which drive is established between an inner drum and an outer drum by two differing clutching arrangements, one of which establishes direct drive and the other of which establishes a reduced slipping drive, in which the necessity for the carrier plate referred to above is eliminated, to also eliminate the cost of the carrier plate and mounting components.
It is another object of the present invention to provide such two-speed drive having a shaft extension for direct drive of the other components in which the necessity for a separate clamping of the shaft extension to the motor shaft is obviated.
It is a further object of the present invention to provide such two-speed drive in which a separate resilient mounting means for the centrifugal clutch shoes is avoided while eliminating the transmission of the vibrations between the inner and outer drums.
It is still another object of the present invention to provide such a drive in which the overall clutch depth is reduced, as well as the auxiliary shaft and the motor shaft lengths, and in which the adequate bearing support of the inner drum is afforded.